The Fifa corruption investigation explained: what is going on in Switzerland?

Is that all?

No. Hours later, Swiss prosecutors launched their own separate inquiry into the bidding process for the 2018 and 2022 World Cups, won by Russia and Qatar respectively. Fifa's headquarters were raided, documents and electronic data seized. In Miami, the FBI raided the offices of regional football federation Concacaf (Confederation of North, Central America and Caribbean Association Football).

The US Attorney General Loretta Lynch also alleged in a news conference that Fifa officials took bribes to help secure the 2010 World Cup in South Africa.

Was Sepp Blatter arrested?

No, the current president was not one of the seven arrested at the Swiss hotel and there have so far been no charges levelled against him. Blatter is seeking a fifth term as Fifa president, with elections scheduled to take place this Friday. Fifa says it plans to continue with the process despite today's developments.

The charged officials include:

• Current Fifa vice presidents Jeffrey Webb and Eugenio Figueredo, and former vice president Jack Warner
• Costa Rica football federation president Eduardo Li, Fifa development officer Julio Rocha, former head of Brazilian football José Maria Marin, former Fifa executive Nicolás Leoz, Venezuela football president Rafael Esquivel and Concacaf attaché Costas Takkas
• Four sports marketing executives and alleged "intermediary" José Margulies.

Why does it matter?

The World Cup is one of the biggest events in sport, but recently serious questions have been raised about the bidding process for hosting the tournament. Fifa refused to publish an internal report into the controversial decision to host Qatar 2022.

But the investigation goes back over 20 years to 1991, with the US Department of Justice statement alleging, "Two generations of soccer officials abused their positions of trust for personal gain, frequently through an alliance with unscrupulous sports marketing executives who shut out competitors and kept highly lucrative contracts for themselves through the systematic payment of bribes and kickbacks."

The contracts included television broadcast details, locations for major international tournaments as well as sponsorship opportunities.

Why the FBI?

"If you touch our shores with your corrupt enterprise you will be held accountable for that corruption," said James Comey, director of the FBI in a recent news conference.

The charges against the Fifa officials include deals related to the 2016 Copa America, set to be hosted in the United States. Concacaf, the governing body responsible for soccer in North, Central and South America, has its base in Miami, Florida.

The US Attorney General also pointed out that the officials used US banking and wire services in the process of their alleged corruption. She highlighted other alleged bribery payments, including those relating to the sponsorship of the Brazilian Football Confederation (CBF) by a major US sportswear brand (in 1996, Nike signed a reported $200 million contract with the CBF to supply kits for the Brazilian national team).

Soccer is a fast-growing sport in the United States, and the investigators claimed that the officials planned to use their gains in order to profit from the game’s expansion in this new market.

Could the tournaments be moved?

At this stage a move is unlikely. Fifa said on Wednesday there was no plan to re-run the bidding process that gave the 2018 World Cup to Russia and the 2022 tournament to Qatar, and the tournament has never been moved before.

Has Fifa said anything about the charges?

"Fifa welcomes actions that can help contribute to rooting out any wrongdoing in football," a statement on the federation's website begins, concluding, "We are pleased to see that the investigation is being energetically pursued for the good of football and believe that it will help to reinforce measures that FIFA has already taken."

Former vice president Jack Warner, who is named in the US Department of Justice's indictment but not as yet arrested, said, "I have been afforded no due process and I have not even been questioned in this matter. I reiterate that I am innocent of any charges. I have walked away from the politics of world football to immerse myself in the improvement of lives in this country [Trinidad and Tobago] where I shall, God willing, die."

What has been the reaction in the UK?

FA chairman Greg Dyke said on BBC Radio 5 Live that it was a "very serious day for Fifa and the leadership of Fifa".

He also suggested that Fifa's presidential election could be delayed given the current circumstances.

Match of the Day presenter Gary Lineker has been following the story online along with thousands more Twitter users.

Danny Baker challenged the FA to withdraw from the next World Cup.

What next?

Fifa insist the presidential elections will go ahead as planned this Friday. The arrests appear to have been timed in order to coincide with the Fifa meeting in Switzerland, when as many indicted officials as possible are in the same place. The hotel, incidentally, was the same venue that David Cameron and Prince William travelled to in 2010 to lobby for support for England's 2018 World Cup bid.

The FA have already lent their support to Blatter's presidential rival, Prince Ali Bin al-Hussein of Jordan, who has said the scandals under the current leadership "cannot continue".

"Fifa needs leadership that governs guides and protects our national associations," he said. "Leadership that accepts responsibility for its actions and does not pass blame.

"Leadership that restores confidence in the hundreds of millions of football fans around the world."

The FBI have confirmed that the investigation is ongoing. When asked about Blatter's status at a recent news conference, US Attorney General Loretta Lynch said she would only comment on those individuals who had been charged.